In the food packaging industry various techniques exist for sequentially packaging containers of food product in alternate environments such as an inert atmosphere to substantially reduce the oxygen level and thereby preserve freshness. Such processes are beneficial for packaging of various food products, including edible nuts, coffee, powdered milk, infant formula, among others. Existing systems have limitations which reduce the efficiency and speed of the packaging operation. In addition, certain packaging system designs remove the choice of using a variety of modern filling and seaming equipment.
For example, techniques are known for flushing the interior of empty containers before filling with contents, to reduce residual oxygen. Techniques are also known for reducing oxygen content in the food material prior to packaging, and for transporting filled containers. However, known apparatus for performing these functions have shortcomings which have prevented their widespread adoption. These include excessive gas consumption, inflexible design which restricts operator access, lower operating speeds, requirements for vacuum sources or bulky apparatus, and long start-up and re-start delays.
By way of example, U.S. Pat. Nos. 3,871,157, 3,942,301 and 4,140,159 and German 0S 3323710 disclose various apparatus for low-oxygen packaging including particular forms of gas distributors and bulk product purging. U.S. Pat. No. 3,860,047 discloses an apparatus for flushing oxygen from bulk material to be packaged, including gas delivery tubes. U.S. Pat. No. 4,094,121 discloses another apparatus for packaging products in substantially oxygen-free atmosphere, including a simple inlet for inserting inert gas to be forced upwards through a filling tube and filling funnel. These known systems all suffer from inflexible structure, undesirably high gas consumption, potential adverse stratification of bulk product as a result of flushing gas flows, and limited speed.
It is therefore desired to provide a system and method for packaging product in selected (e.g. inert) environments using generally open and accessible structures. Further, it is desirable to provide such a system which will permit very low residual oxygen levels in packaged product, while consuming less inert gas and avoid stratification of bulk material. Finally, it is highly desirable to provide such an integrated gassing system which is adaptable to containers having multiple sizes, and is usable at high throughputs.